1. Field of the Invention
The present invention relates generally to the field of binoculars and other viewing devices. More specifically, it relates to a foldable binocular apparatus which collapses into a flat configuration for convenient storage in a plastic pocket case. The apparatus includes a body formed from a blank of flexible, resilient sheet material divided by fold lines into several regions including a distal wall having a pair of longitudinally spaced-apart objective lens ports. A bottom wall extends from a longitudinal edge of the distal wall and has a lateral fold line to permit the body to collapse for apparatus focusing and for storage. A top wall extends from an opposing longitudinal edge of the distal wall and has a lateral fold line to also permit the body to collapse. A proximal wall extends from an edge of the top wall opposite the distal wall and has a pair of longitudinally spaced-apart eyepiece ports. A bonding flap extends from a longitudinal edge of the proximal wall opposite the top wall for bonding to the remote longitudinal edge of the bottom wall during apparatus assembly. Two light blocking side walls extend from opposing lateral edges of the distal wall, each side wall having a central lateral fold line to permit the side wall to collapse simultaneously with the top and bottom walls during apparatus focusing and storing. Each side wall has a bonding tab at its remote end to bond to a bonding section on the outer face of the proximal wall at each proximal wall lateral edge. Eyepieces and objective lenses each have a radial flange along one perimetrical edge and a pair of opposing radial tabs along the other perimetrical edge. The eyepieces and objective lenses are fit into their respective ports, and the tabs fit through port edge notches and then rotate out of alignment with the port notches. The assembled apparatus includes a binocular body which collapses at the fold lines in the manner of a bellows to permit the proximal and distal walls to move toward and away from each other to focus the apparatus for an infinite variety of viewing distances, and to collapse into a flat storage configuration to fit into a storage and carrying envelope. The apparatus optionally includes a nose receiving opening cut into the proximal and bottom walls midway between the eyepieces.
2. Description of the Prior Art
There have long been binocular devices formed of blanks of sheet material for assembly into functioning binocular units. These prior devices have generally either not been capable of adjustable focusing for varying viewing distances, or have been structurally weak or complex and difficult to assemble.
Green, et al., U.S. Pat. No. 4,268,111, issued on May 19, 1981, discloses foldable binoculars having a case formed of sheet material. Green includes a rear wall having ports in which two eyepieces are mounted, and a front wall having ports in which two objective lenses are mounted. The front and rear walls are joined together by collapsible case walls which buckle at central, lateral fold lines for focusing and storage. A pair of interconnecting V-shaped openings in the rear and bottom walls permit relative lateral movement of the eyepieces to accommodate users of various eye spacings. A problem with Green et al. is that the blank from which the case is formed has numerous and redundant folding sections, making assembly puzzling and complicated. See Prior Art FIGS. 1 and 2. The eyepiece ports are each formed from the overlap of three mutually registering ports in separate blank wall sections located at three extremities of the blank, causing confusion, complication and a potential for error during assembly of the unit.
Rice, U.S. Pat. No. 4,846,553, issued on Jul. 11, 1989, teaches a foldable stereoscopic viewer for insertion as a disassembled blank into a pocket in a publication, such as a magazine or book. An anchor section of the blank fits into the pocket to removably retain the viewer within the publication. The viewer is assembled by the publication reader into a bellows-like structure similar to that of Green, except that the side walls are formed of two sections 100 and 122, and 96 and 118, connected together at the central side wall fold area. See Prior Art FIGS. 3 and 4. A problem with this construction is that the side walls bend most at the central fold line where the sections are bonded together, increasing the likelihood of bond failure and disconnection. This construction is inherently weak and unreliable.
Hoeptner, U.S. Pat. No. 4,964,709, issued on Oct. 23, 1990, reveals a foldable. binocular device. The Hoeptner device is much like that of Green, except that a visor portion protrudes over the upper edge of the front wall. A problem with Hoeptner is that the blank from which it is assembled is complex and confusing, having eyepiece and objective lens ports formed of multiple registering openings. The blank is also of weak design because the side walls are each joined to the rest of the blank by only two very narrow connecting links. These side walls could break away during assembly and be damaged or lost.
Ohno, U.S. Pat. No. 4,478,498, issued on Oct. 23, 1984, discloses a foldable binocular assembly constructed from a blank. The blank folds into a box-like body having a pair of eyepieces mounted in ports in a rear wall and a pair of objective lenses mounted in ports in a front wall. Ohno folds flat for storage in a carrying case. A problem with Ohno that the box body apparently does not contract or collapse to permit variable focusing for different viewing distances. If Ohno did collapse in the manner of Rice, the side walls would be subject to failure because they are formed of two joined side sections meeting at the centered, fold line area.
Bresahan, U.S. Pat. No. 4,773,747, issued on Sep. 27, 1988, teaches a foldable binocular and binocular blank. It is not clear from the disclosure whether Bresahan is intended to vary its focus by folding or whether it simply folds to collapse for storage. If Bresahan does not have variable focus, this omission limits its usefulness; and if it does fold to vary focus, the structure is weak as in Ohno because the side walls are joined at the fold line from separate side sections.
Justice, Sr. et al., U.S. Pat. No. 4,239,328, issued on Dec. 16, 1980, discloses a collapsible binocular and binocular blank. Justice folds to form a box-shaped binocular body of fixed optical length. The problems of Justice are essentially those of Bresahan.
Riley, U.S. Pat. No. 4,013,341, issued on Mar. 22, 1977, reveals a collapsible binocular instrument having two spaced-apart and interconnected telescoping tube portions. The instrument collapses into a flat configuration for carrying and storage. An ocular lens is inserted into one end of each telescoping portion and an objective lens is inserted into the other end. A problem with Riley is that two blanks are required to construct it, one for each telescoping section of the tube portions. This multiples production equipment requirements and complicates assembly. Another problem is that the lenses must be removed when the instrument is collapsed for carrying and storage, and thus there is the inconvenience of reinserting them for each use.
Harlow, U.S. Pat. No. 2,071,120, issued on Feb. 16, 1937, teaches a magnifying and viewing device for viewing strips of film. A problem with Harlow if used as a binocular body is that it is of fixed optical length, and thus not capable of focusing for varied viewing distances. The Harlow body structure, moreover, does not lend itself to bellows-like collapsing for focusing because the box corners along connecting side edges do not all separate to bow apart from each other.
It is thus an object of the present invention to provide a collapsible binocular apparatus which is formed from a blank which is simple and easy to assemble.
It is another object of the present invention to provide such an apparatus which is sturdy and capable of prolonged and repeated manipulation and collapse without structural failure.
It is still another object of the present invention to provide an apparatus which fits into a carrying case and has a neck strap for convenient access such as at sporting and cultural events.
It is finally an object of the present invention to provide such an apparatus which is inexpensive to manufacture.